Understanding Styles in Microsoft Word - A Tutorial in the Intermediate Users Guide to Microsoft Word

"... Styles are arguably the most important feature in Microsoft Word. Why? Because everything that you do in Word has a style attached. The definition of a style is two-fold. First, you can think of a style as a set of pre-defined formatting instructions that you can use repeatedly throughout the document. Let's say each heading in a document must be centered, uppercase, bold, and a slightly larger font size. Each time you need to apply formatting to the heading, you have to go through the entire process to get the text the way you want it. If you store the formatting commands in a style, you can apply that style any time you need it without having to do all of the reformatting.

Possibly more important however is that styles are used to "tag" or identify parts of a document. An example of this is whether text is part of a heading, a footnote, a hyperlink, or body text. These are all examples of styles in Word. ..."